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Nickel-based superalloy DZ125 was first sprayed with a NiCrAlY bond coat and followed with a nanostructured 2 mol% Gd_2O_3-4.5 mol% Y_2 O_3-ZrO_2(2 GdYSZ) topcoat using air plasma spraying(APS). Hot corrosion behavior of the as-sprayed thermal barrier coatings(TBCs) were investigated in the presence of 50 wt%Na_2SO_4 + 50 wt% V_2O_5 as the corrosive molten salt at 900 ℃ for 100 h. The analysis results indicate that Gd doped YVO_4 and m-ZrO_2 crystals were formed as corrosion products due to the reaction of the corrosive salts with stabilizers(Y_2O_3, Gd_2O_3) of zirconia. Cross-section morphology shows that a thin layer called TGO was formed at the bond coat/topcoat interface. After hot corrosion test, the proportion of m-ZrO_2 phase in nanostructured 2GdYSZ coating is lower than that of nano-YSZ coating. The result reveals that nanostructured 2GdYSZ coating exhibits a better hot corrosion resistance than nano-YSZ coating.
Nickel-based superalloy DZ 125 was first sprayed with a NiCrAlY bond coat followed by a nanostructured 2 mol% Gd 2 O 3 -4.5 mol% Y 2 O 3-ZrO 2 (2 GdYSZ) topcoat using air plasma spraying (APS). Hot corrosion behavior of the as- sprayed thermal barrier coatings (TBCs) were investigated in the presence of 50 wt% Na_2SO_4 + 50 wt% V_2O_5 as the corrosive molten salt at 900 ° C for 100 h. The analysis results indicates that Gd doped YVO_4 and m-ZrO_2 crystals were formed as corrosion products due to the reaction of the corrosive salts with stabilizers (Y_2O_3, Gd_2O_3) of zirconia. Cross-section morphology shows that a thin layer called TGO was formed at the bond coat / topcoat interface. -ZrO 2 phase in nanostructured 2GdYSZ coating is lower than that of nano-YSZ coating. The result reveals that nanostructured 2GdYSZ coating exhibits a better hot corrosion resistance than nano-YSZ coating.